Method of preparing metal stock



May 18, 1937. R. L. TEMPLINI METHOD OF PREPARING METAL STOCK Filed June22, 1934 INVENTOR firm/74rd A7207 ///2 ATT RNEY Patented May 18, 1937UNITED STATES PATENT OFFICE LIETHOD OF PREPARING METAL STOCK ApplicationJune 22, 1934, Serial No. 731,876

19 Claims.

The invention relates to metal working and in particular concerns thepreparation or improvement of forging stock or of metal stock ingenera].

In the metal working arts recognition has been accorded to thebeneficial effects of working in relation to grain refinement andimprovement in mechanical properties of the metal. Inseparable from theadvantages which may be said to result from the working methods commonlyemployed, as in rolling or drawing, are certain inherent disadvantages.Perhaps one of the most important of these is represented by thephenomenon generally referred to as the production of directionalproperties in the metal. Thus it is well known that in the case ofrolled shapes, for example,

the tensile strength will be greater in the direction of rolling thantransversely thereto. Many attempts have been made to avoid or minimizethe directional effect of rolling and kindred working operations but, sofar as I am aware, none of the methods now known to the art arecompletely effective; and in some cases they are of doubtful value.

The designs of roll passes and. of forging dies are illustrative of themeans commonly adopted to work the metal in such a way as to tend towardrefinement of the grain structure and the elimination of directionalproperties. The improvement obtainable by such expedients is quitelimited, however, and is largely dependent upon size and shape of themetal stock which is used, in relation to the size and shape of theproduct or intermediate product which is to be fabricated.

It is an object of the present invention to provide a. method ofpreparing metal stock which is characterized by substantial freedom fromdirectional properties and which will show in this respect a far greaterimprovement than is obtainable by any of the methods which heretoforehave been employed. Another object is to provide a method of preparingmetal stock characterized by an improvement in mechanical properties andmore particularly by an increased fatigue limit.

A more. specific object of my invention is to teach a method ofpreparing aluminum stock which is characterized by freedom fromdirectional properties and by an attendant improvement in physicalproperties in all directions with a marked improvement in fatigue limit.I have conducted fatigue tests on specimens cutout of large aluminumalloy forgings such as are made for locomotive connecting rods and havefound that the fatigue strength is appreciably below that of wroughtmetal of similar composition produced in smaller sizes, such as rod orsheet or even small forgings. It is therefore a special object of myinvention to provide a method of preparing aluminum forging stocksuitable for use in. the fabrication of locomotive connecting rods,airplane propellers and similar articles ,where the amount of workingnormally performed in the fabricating steps is comparatively small byreason of limitations imposed by the size of ingot or stock available.The method which is described herein will also be found applicable,however, in the production of smaller articles by forging or by otherfabricating methods since in every case it will be found possible tostart the forming operations with stock more nearly conforming to thesize of the article which is to be made; and since the stock which isproduced in accordance with the method described is quite free fromdirectional properties, the product will also be comparatively free fromdirectional properties. This, of course, would not be true where formingoperations are relied upon for the grain refining effect, in which casethere is always a tendency toward production of directional properties.Where cold working must be relied upon for the production of optimummechanical properties it is likewise possible to start the formingoperations with stock more nearly conforming to the size of the articlewhich is to be made.

These are the principal objects of the invention. Others will appearfrom the following description in which there will be occasion to referto the appended drawing in which Fig. 1 shows in perspective a metalingot r billet suitable for processing in accordance with my novelmethod. Fig. 2 shows the same billet at the end of the first step of themethod. Fig. 3 is a perspective view of a blank for a locomotive siderod forging such as would be produced in accordance with my inventionfollowing the working or kneading steps indicated in Figs. 1 and 2.

Fig. 4 shows a cast or machined billet such as commonly employed inextruding operations; and

Fig. 5 shows the same body after it has been subjected to the first stepof my method which, in the specific embodiment illustrated, has beenperformed by die expressing or, as more commonly referred to, byextrusion.

I have found that if an elongated ingot or billet be first upset in onedirection and then worked back as by forging or extrusion tosubstantially its original form, with a number of repetitions of thiscycle, a very considerable improvement in mechanical properties isobtained and the forging stock or other stock so produced possessesphysical properties which are very simibetween successive working cyclesor between lar in all directions. It is particularly to be'obsuccessivesteps of a given cycle.

served that in this cyclical process which I have Figs. 4 and 5 areintended to indicate the sucdevised the working-or kneading of the metalis cessive forms of a. billet when processed in acaccomplished withoutany reference whatsoever cordance with my method when the kneading is 5to the form or shape of the article which subseto be accomplished byextrusion instead of by quently is to be produced therefrom. Thus it isforging, Fig. 4 representing the billet at the bepossible to carry theprocess through the reginning and end of the cycle and Fig. 5representquired number of cycles to produce optimum ing the intermediateform of the billet. when the properties irrespective of the form of theproduct kneading is to be performed by extrusion I prefer 1 orsubsequent methods of fabrication. Hence, the a reduction of at least 50per cent in the cross secinventionas I have conceived it relates to thetional area of the billet, with a corresponding preparation of stock,and the'method employed is elongation. Thereafter the extruded billet isrecharacterized by its cyclical nature and by the turned tosubstantially its original form by an upfact that the metal is workedback to its original setting or die forging operation. Apparatus byform-or to substantially its original form-"one which the originalbillet 3 may be extruded to or more times. form the elongated billet 4is well known in the Throughout the balance of the specification art andneed not be here described. One form and in the appended claims the termbillet is of app ratu suitable for returning b t t used in a genericsense and will be understood its original form 3 is described in myeopendmg to include, for example, the "ingot" and the app Serial 7issued February 4. bloom as well as the billet as these terms are 1936.as Patent No. 2, 0. customarily employed. This definition is'necessi- Itwill be seen that the method described in tated by reason of the factthat the method as. connection with Figs. 4 and 5 is the same as scribedcan be performed either by forging or by that described in connectionwith Figs. 1 and 2, extrusion and the terminology in the two fields theonly difference being in the apparatus which is not entirely consistent.The cast body of is utilized in the performance of the method. aluminum,for example, that is used in extruding In each case the billet I or 3 issubjected shapes is generally known as an extrusion billet" to amechanical worlnng cycle consisting in whereas the cast body of metalused in rolling is deforming it by the application of a working calledan ingot. It willbe understood that the pressure and returning thedeformed billet (2 body of metal shown in Fig. 1 asthe starting point or4) to substantially its original form by furof the process may, properlyspeaking, be neither ther application of a working pressure. In each aningot nor a billet but a block of metal cut out case this working cycley be r p a ed a sufof an ingot; This also comes within the purviewficient number of times to produce optimum of my definition of the termbil1et" as used P y a Properties and maximum fatigue herein. sistance. Ihave found, however, that when The term aluminum as used herein and inthe method is performed by the combined steps of the appended claims isintended to comprise both extrusion and die forging two or three cyclesare aluminum and alloys in which aluminum forms usually sufficient oproduce p m P p r 40 the principal constituent. in aluminum. After thethird cycle the alumium The billet I may be cast as an ingot or it maybe a y t t d showed greatly mp P p lproduced in any convenient mannerfrom alarger ties and ftu'ther repetitions of the cycle did not body ofmetal, Assuming that; it is d sired t produce any substantial change.The mechanical make stock for forging, the amount of metal in propertiesinvestigated include tensile strength, 5 billet I should be about thatwhich will be reyield strength, elongation and reduction in area. quiredto prod 'ce the finished forging. Bill t l i It will of course beunderstood that some alumiupset as by press or hammer forging, into thenum loy m y require a greater number of form shown by the dotted lines2, the forging p t t s f t cycle th n thers. pressure being applied inthe direction indicated As an example whereby the exact nature of by thearrow 11. The upset billet 2 is then turned my invention may becompletely understood refup on one of its sides, as shown in Fig. 2, anderence will be made tothe production of side fqrging pressure applied inth direction of t rods for locomotives. For this purpose alumiarrow b.It is then turned between the forging mlm alloy e nss h ve rapidly beenincreasing dies so that pressure can also be applied in the in favor byreason of their strength and lightdi ect on of the ar ow-6., By-means offorging ess. The weight consideration is particularly pressures b and cthe upsetybmetz is important in machine parts having rapid reback againto substantially the form or the ciprocatory motion, from the standpointof avoiding inertia losses and in the case of locomotive ori 1 ill tI,asindicatedb the otted lines at I l u tile dimension C i: appiximately the side rods the reduction in welght is especially 69 0important since it reduces the rail hammer Same as the helgm C of theoriginal bmet The caused'by the reciprocating parts. As previously stepsof upsetting and returning the indicated, the problem of attainingsatisfactor formed billet to substantmny its original form are fatiguelimits in large forgings of this sort i then repeated number of times- IPrefer to much more serious than in the case of wrought c5 P the cycleat least three times and in some metal of similar composition producedin smaller cas s it may be desirable that it be repeated sizes, such asrod or sheet or smaller forgings. A six times or more. In the case ofaluminum it is 7 x 7 x 15 inch billet was taken from a 20 x 20 x72Preferable 7 out the Opera-b10118 0f upsetting inch aluminum alloy ingotcontaining approxiand drawing at an v d temperature mately 45 per centof copper, 0.8 per cent silicon, 7 tween 500 F. and 840 F. isrecommended in the and 0.8 per cent manganese. This billet was upcase ofvery large forgings. I have in contemplaset to a 9 inch cube, then drawnback again to tion however, the Possibility of kneading the its originaldimensions. This cycle was repeated metal at o temperature Whereelevated six times and then the billet was reduced 50 peratures aredesired reheating may be effected per cent at one end, as at 5 in Fig.3, and 80 75 ing were carried out between temperatures of 840 F. and 500F. Specimens taken from a finished forging blank and subjected to arotating beam fatigue test, showed an average endurance limit in thetransverse direction of 13,000 pounds per square inch, based on500,000,000 cycles, as compared with an average endurance limit in thesame direction of 11,000 pounds per square inch for specimens taken fromblanks forged in the usual manner. It will be observed that thisrepresents an improvement of about 18 per cent over the resultsobtainable by the methods known to the prior art. Longitudinal andtransverse test specimens showed the following average values fortensile and yield strengths:

. Transverse Transverse Longlmdma] (vertical') (horizontal) Tensilestrength (pounds per sq.

in.) 56025 54860 55100 Yield strength (pounds per sq.

As viewed in Fig. 3. It will be seen from these results that. theforgings produced showed very little tendency toward directionalproperties.

Similar tests were made on specimens taken from 99 per cent aluminumstock prepared in accordance with the specific embodiment of my methoddescribed with reference to Figs. 4 and 5 of the drawing. The results ofthese tests are given in the table:

At the comple- At the completion of 2 cycles tion of 4 cycles Longi-'Irans- Longi- Transtndinal verse tudinal verse Tensile strength(lbs/sq. in.) 22310 22240 21630 22110 Yield strength (lbsJsq. in.) 1960020300 18300 21600 Percent elongation 17.5 18.0 18.0 18.0

The foregoing data give a comparison between longitudinal and transverseproperties both at the end of the second cycle and at the end of thefourth cycle; that is, in the first case the extrusionand upsetting tothe original form is performed twice and in the second case four times.The results clearly show that stock prepared in accordance with themethod disclosed herein is characterized by substantial freedom fromdirectional properties.

It will be seen that by my invention I have provided' a method ofpreparing metal stock which can conveniently be performed with existingequipment; which results in improved mechanical properties-especially asto fatigue limits; and effects a marked decrease in tendency towarddirectional properties. The method which I have devised also makespossible the production from standard sizes of ingot, of large aluminumalloy forgings characterized by a high fatigue limit.

I claim:

1. Method of preparing metal stock characterbillet, mechanicallydeforming said billet by the application of a working pressure, andreturning the deformed billet tosubstantially its original form byfurther application of a working pressure.

2. Method of preparing metal stock which comprises providing a metalbillet, subjecting said billet to a mechanical working cycle consistingin deforming the billet by the application of a working pressure andreturning the deformed billet to substantially its original form byfurther application of a working pressure, and repeating said mechanicalworking cycle at least two times.

3. Method of preparing metal stock characterized by substantial freedomfrom directional properties which comprises providing a metal extrusionbillet, reducing the cross sectional area of said billet by extrusionthrough a die, and' returning the extruded billet to substantially itsoriginal form by an upsetting operation.

4. Method of preparing metal stock characterized by substantial freedomfrom directional properties which comprises providing a metal extrusionbillet, reducing the cross sectional area of said billet by extrusionthrough a die, and returning the extruded billet to substantially itsoriginal form by a die forging operation.

5.-Method of preparing metal stock which comprises providing a metalbillet, subjecting said billet to a mechanical working cycle consistingin reducing the cross sectional area of said billet by extrusion througha die and returning the extruded billet to substantially its originalform by an upsetting operation, and repeating said mechanical workingcycle at least two times.

6. Method of preparing metal stock which comterized by substantialfreedom from directional properties which comprises providing a. metalbillet, upsetting said billet by applying a forging pressure in thedirection of its longest dimension, and returning said upset billet tosubstantially its original form by drawing out through forging dies. v

8; Method of preparing metal stock characterized by substantial freedomfrom directional properties which comprises providing a metal billet,upsetting said billet by applying a forging pressure in the direction ofits longest dimension, and returning said upset billet to substantiallyits original form by the further application of forging pressure indirections normal to the initial forging pressure.

9. Method of preparing metal stock which comprises providing a metalbillet, subjecting said billet .to a mechanical working cycle consistingin upsetting said billet by applying a forging pressure in the directionof its longest dimension and returning said upset billet tosubstantially its original form by drawlngout through forging dies, andrepeating said mechanical working cycle at least two times.

10. Method of preparing metal stock which comprises providing a metalbillet, subjecting said billet to a mechanical working cycle consistingin upsetting said billet by applying a forging pressure in the directionof its longest turning the extruded billet dimension and returning saidupset billet to sub-' stantially its original form bythe furtherapplication of forging pressure in directions normal to the initialforging pressure, and repeating said mechanical working cycle at leasttwo times.

' 11. Method of preparing aluminum stock characterized by substantialfreedom from directional properties which comprises providing analuminum billet, mechanically deforming said billet by the applicationof a working pressure, and returning the deformed billet tosubstantially its original form by further application of a workingpressure. I 12. Methodof preparing aluminum stock which comprisesproviding an aluminum billet, subjecting said billet to a mechanicalworking cycle consisting in deforming the billet by the application of aworking pressure and returning the deformed billet to substantially itsoriginal form by further application of a working pressure, andrepeating said mechanical working cycle at least two times.

13. Method of preparing aluminum stock characterized by substantialfreedom from directional properties which comprises casting an aluminumextrusion billet, reducing the cross sectional area,

of said billet by extrusion through a die, and reto substantially itsoriginal form by an upsetting operation.

14. Method of preparing aluminum stock which comprises providing analuminum extrusion billet,

subjecting said billet to a mechanical working cycle consisting inreducing the cross sectional area of said billet by extrusion through adie and returning the extruded billet to substantially its original formby an upsetting operation, and repeating said mechanical working cycleat least two times.

15. Method of preparing aluminum stock characterized by substantialfreedom from directional properties which comprises providing analuminum extrusion billet, reducing the cross sectional area of saidbillet by extrusion through a die, and returning the extruded billet tosubstantially its original form by a die forging operation.

16. Method of preparing aluminum stock char acterized by substantialfreedom from directional properties which comprises providingan aluminumbillet, upsetting said billet by applying a forging pressure dimension,and returning said upset billet to substantially its original form bydrawing out through forging dies.

17. Method of preparins aluminum stock characterized by substantialfreedom from directional dimension and returning said upset billet tosubstantially its original form by drawing out through forging dies, andrepeating said mechanical working cycle at least two times.

19., Method of preparing aluminum stock. which comprises providing analuminum billet, subjecting said billet to a mechanical working cycleconsisting in upsetting said billet by applying a forging pressure inthe direction of its longest dimension and returning said upset billetto substantially its original form by the further application of forgingpressure in directions normal to the initial forging pressure, andrepeating in the direction of its longest said mechanical working cycleat least two times.

RICHARD L. TEM'PLIN.

